CN1236623C - Information ontropy holding decoding method and device - Google Patents

Abstract

The present invention discloses an information entropy holding decoding method and a device thereof. The two-dimensional combined information entropy holding length variation decoding of variables X1 and X2 can be realized thought looking up a two-dimensional code list. If code words extracted from a code stream are in one-to-one correspondence with information groups {X1=Xn, X2=ym} in the code list, the decoding can be carried out to obtain {X1=Xn, X2=Ym}; otherwise, the code word can be a first composite signal; a code word following the code word is a second composite signal; the method is used for decoding. The present invention has a goal to decode the code stream with a high corresponding compression efficiency generated by the information entropy holding decoding method and a device thereof. The present invention is mainly used in a code stream decoder for the two-dimensional combined information entropy holding length variation decoding for digital signals, and the present invention can also be used for decoding the code stream of multiple-dimensional combined length variation decoding. The present invention is especially suitable for decoding image or video compression.

Description

Information entropy preserving decoding method and device

technical field

The invention relates to the technical field of electrical digital data processing, in particular to an information entropy preserving decoding method and device.

Background technique

The two-dimensional joint information entropy-preserving variable-length coding of the variables X ₁ and X ₂ is often realized by looking up the two-dimensional code table. When the value range of variables X ₁ and X ₂ is very large, if one-to-one correspondence between the information combination {X ₁ , X ₂ } and codewords is used, the two-dimensional code table will be very large, which is not conducive to storage and search. The usual method is to use a look-up table to implement encoding for the information combination {X ₁ , X ₂ } with a high probability of occurrence, and to obtain a control code word by looking up the table for the combination {X ₁ , X ₂ } with a low probability of occurrence. This control code word is only used to mark that the encoding of the event cannot be directly realized by looking up the table, and the information of X ₁ and X ₂ will be carried by other code words immediately behind the control code word.

For the {X ₁ , X ₂ } combination that cannot be coded directly by looking up the table, the commonly used coding method is to code X ₁ and X ₂ separately in sequence after the control codeword. The disadvantage of this method is that the correlation between X ₁ and X ₂ is not used, and the control codeword is only used as a mark, and does not carry some information about X ₁ or X _2. There is redundancy, which is not conducive to compression efficiency improvement.

A new entropy-preserving coding method adds part of the information of X ₁ and X ₂ to the control codeword for coding, and the remaining part of information is coded according to the coded information, which improves the compression efficiency of entropy-preserving coding.

Contents of the invention

The present invention provides an information entropy preserving decoding method and device, which are used to correctly decode the code stream generated by the new information entropy preserving encoding method and device in the background art.

In order to achieve the above object, the technical scheme adopted in the present invention is as follows:

1. An information entropy-preserving decoding method, including if the code word extracted from the code stream is in one-to-one correspondence with the signal combination {X ₁ =x _n , X ₂ =y _m } in the code table, then the decoded {X ₁ = x _n , X ₂ =y _m }; if the code word extracted from the code stream does not have a one-to-one correspondence with the signal combination {X ₁ =x _n , X ₂ =y _m } in the code table, then the code word is The first composite signal, the next codeword following it is the second composite signal, and its decoding steps are as follows:

1) Subtracting a specific control codeword from the first synthesized signal, thereby decoding the first signal X ₁ or the second signal X ₂ ;

2) Decoding another signal from the second composite signal based on the decoded information.

The said subtracting a specific control codeword from the first synthesized signal so as to decode the first signal X ₁ or the second signal X ₂ includes:

1) Subtracting a specific control codeword from the first synthesized signal;

2) The signal obtained by subtracting the control codeword from the first synthesized signal is mapped and decoded by the function f(x) to obtain the value of the first signal X ₁ or the second signal X ₂ , and at the same time obtain a control of another undecoded signal information, where the argument of f(x) is the signal obtained by subtracting the control codeword from the first synthesized signal.

Said decoding another signal from the second synthesized signal according to the decoded information includes:

1) Map the decoded signal through the function u(x);

2) adding the signal obtained through the function u(x) mapping to the second composite signal;

3) The other signal is decoded using the added signal and one of the control information described above.

2. A device for keeping information entropy decoding, including a table look-up device for the input codeword to look up a two-dimensional variable-length decoding table, if the codeword extracted from the code stream is combined with the signal in the code table {X ₁ = x _n , X ₂ =y _m } one-to-one correspondence, then the decoded signal combination {X ₁ =x _n , X ₂ =y _m }; if the input code word does not match the signal combination in the two-dimensional variable-length decoding table {X ₁ , X ₂ } one-to-one correspondence then input the input codeword and the next codeword following it into the demultiplexing device;

1) demultiplexing means for separating the first composite signal and the second composite signal;

2) Subtracting a specific control codeword from the first synthesized signal for decoding the information extraction device of the first signal _X1 or the second signal _X2 ;

3) an information restoration device for decoding another signal from the second composite signal based on the decoded information;

The demultiplexing device is respectively connected with the information extraction device and the information restoration device, the control code word is connected with the input end of the information extraction device, and the information extraction device is connected with the information restoration device.

The information extraction device includes:

1) Subtraction device;

2) A first information restoration device for realizing the function f(x), decoding X ₁ or X ₂ , and simultaneously obtaining a control information of another signal that has not been decoded;

When the output of the table look-up device was a control code word, the first composite signal and the control code word were connected to the input of the subtraction device respectively; the output of the subtraction device was connected with the first information restoration device; the X ₁ or the output of the first information restoration device X ₂ , and the control information is connected with the information restoration device.

The information restoration device includes:

1) Adding device;

2) a mapping device for realizing the function u(x);

3) A second information restoring device for decoding _X2 ;

The X ₁ or X ₂ that the information extraction device decodes is connected to the input of the mapping device; the output of the mapping device is connected to the input of the adding device; the second composite signal is connected to another input of the adding device; the adding device is connected to the second The information restoration device is connected; the control signal output by the information extraction device is connected with the second information restoration device for transmitting control information; the second information restoration device outputs X ₂ .

The beneficial effect of the present invention is that it fully realizes the decoding of the code stream generated by the new information entropy preserving coding method in the background technology. The invention is mainly applied in a decoder for two-dimensional joint information entropy maintaining variable-length coded streams for digital signals, and can also be extended to a decoder for multi-dimensional joint variable-length coded streams. The invention is especially suitable for image or video compression decoding.

Description of drawings

Fig. 1 is the functional block diagram of device of the present invention;

Fig. 2 is a structural block diagram of the components of the device of the present invention.

Detailed ways

In the process of compression encoding and decoding of image data and video data, the one-dimensional coefficient after transformation, quantization and scanning is composed of n (n≥0) 0s and one non-zero coefficient appearing alternately. The value of a non-zero coefficient is level, and the number of coefficients whose value is 0 before the non-zero coefficient is called the run length run. The decoding of the transformed and quantized coefficients is often done by looking up the two-dimensional code table and decoding the {level, run} combination. The present invention is applicable to the combination of {level=x _n , run=y _m } to decode the two-dimensional joint information entropy-preserving encoded code stream. The following is an embodiment of the present invention:

Example 1

1. A kind of information entropy keeps decoding method, comprises the following steps:

1) Input the code word extracted from the code stream into the table look-up device, check the two-dimensional variable-length decoding table, if the code word is in one-to-one correspondence with the {level=x _n , run=y _m } combination in the code table, then The decoded {level=x _n , run=y _m } combination; if the input code word does not have a one-to-one corresponding signal combination {level=x _n , run=y _m } in the two-dimensional variable-length decoding table, The table look-up device outputs a specific control code word, and simultaneously inputs the input code word and the next code word following it into the demultiplexing device, and the demultiplexing device outputs the input code word as the first composite signal and The subsequent next codeword is output as the second composite signal;

2) The decoding steps of the first composite signal and the second composite signal are as follows:

The first composite signal and the specific control codeword are input to the information extraction device, and the first composite signal is subtracted from the specific control codeword in the information extraction device, thereby decoding to obtain the value of run;

The second composite signal and the decoded information are input to the information restoring device, and the value of level is decoded from the second composite signal according to the decoded information.

2. As mentioned in point 1, the specific control codeword is subtracted from the first composite signal to decode the value of run. The method is as follows:

1) the first composite signal and the specific control codeword input subtraction device 701, the first composite signal subtracts the specific control codeword in the subtraction device 701, and the specific control codeword is equal to 59 in this example;

2) Input the signal obtained by subtracting the specific control codeword from the first synthesized signal into the first information restoration device 703, and input the value of run obtained by mapping and decoding the function f(x) into the first information restoration device 703, and at the same time obtain the level The symbol information of , where the function of f(x) is to binarize the lowest bit of the input x, and output it as the symbol information of level, and shift x to the right by one bit to obtain the value of run.

3. According to the decoded information mentioned in point 1, the value of level is decoded from the second composite signal as follows:

1) The run input mapping device 705 is mapped by the function u(y _m ), wherein the function realized by the function u(y _m ) is to find |x _l | for run=y _m , where {level=|x _l |, run= y _m } cannot be decoded by looking up the table and {level=|x _l |-1, run=y _m ,} can be decoded by looking up the table, then u(y _m )=|x _l |;

2) Both the output of the mapping device 705 and the second composite signal are input to the addition device 704, and the signal |x _l | obtained by mapping the function u(y _m ) is added to the second composite signal to obtain the absolute value information of level;

3) The absolute value information of the level and the sign information of the level obtained in the second point are input to the second information restoration device 706 and decoded to obtain the value of the level.

Example 2

1. A kind of information entropy keeps decoding method, comprises the following steps:

1) Input the code word extracted from the code stream into the table look-up device, check the two-dimensional variable-length decoding table, if the code word is in one-to-one correspondence with the {level=x _n , run=y _m } combination in the code table, then Decode {level=x _n , run=y _m } combination; if the input code word does not have a one-to-one corresponding signal combination {level, run} in the two-dimensional variable-length decoding table, the table look-up device outputs a specific Control the code word, input the input code word and the next code word immediately after it into the demultiplexing device at the same time, and the demultiplexing device outputs the input code word as the first composite signal and outputs the next code word following it The code word is output as a second composite signal;

2) The decoding steps of the first composite signal and the second composite signal are as follows:

The first composite signal and the specific control codeword are input to the information extraction device, and the first composite signal is subtracted from the specific control codeword in the information extraction device, thereby decoding to obtain the value of run or level;

The second composite signal and the decoded information are input to the information restoring device, and another signal is decoded from the second composite signal based on the decoded information.

2. As mentioned in point 1, subtract a specific control codeword from the first composite signal to decode the value of run or level. The method is as follows:

1) the first composite signal and the specific control codeword input subtraction device 701, the first composite signal subtracts the specific control codeword in the subtraction device 701, and the specific control codeword is equal to 59 in this example;

2) Input the signal x obtained by subtracting the specific control codeword from the first synthesized signal into the first information restoration device 703, and in the first information restoration device 703, the value of run or level is obtained by mapping and decoding the function f(x), f The function of (x) is to decode the value of run if x<64, and run is equal to x, otherwise (that is, x≥64), the lowest bit of the value of (x-64) is binarized as the symbol information of level, and at the same time (x-64) Move one bit to the right to obtain the absolute value information of level, and then decode the value of level by the sign information of level and the absolute value information of level, and the control information output by f(x) is 0.

3. Based on the decoded information mentioned in point 1, another signal is decoded from the second composite signal, as follows:

1) The signal run or level decoded in the second point is input to the mapping device 705, and is mapped to 0 by the function u(x);

2) Both the output of the mapping device 705 and the second composite signal are input to the addition device 704, and the signal 0 mapped by the function u(x) is added to the second composite signal to obtain the signal z;

3) Input the signal z into the second information restoration device 706. If the value decoded in the second point is the value of run, the second information restoration device decodes the value of level, and takes the lowest bit of z after binarization as the sign information of level , at the same time, move z to the right by one bit to obtain the absolute value information of level, and then decode the value of level by the symbol information of level and the absolute value information of level; if the value of level is decoded in point 2, the second information is restored The device decodes the value of run, which is equal to z.

The above device for entropy preserving decoding method for improving compression efficiency can use a processor system, a microcontroller, a programmable logic device or a hardware circuit to realize part or all of the operations. Some of the operations described above can be implemented in software, while others can be implemented in hardware.

For convenience, these operations are described as different interconnected functional units or as different software modules. However, this is not necessary. In some applications, these functional units or modules may be integrated into a single logic device, program or operation without sharp boundaries. In any case, the functional units and software modules or described features may be implemented independently or in hardware or software together with other operations.

Claims (4)

1. if a comentropy keeps coding/decoding method, comprises code word of extracting from code stream and the signal combination { X in the code table ₁=x _n, X ₂=y _mCorresponding one by one, then decode { X ₁=x _n, X ₂=y _m, if the code word from code stream, extracted not with code table in signal combination { X ₁=x _n, X ₂=y _mCorresponding one by one, then this code word is first composite signal, next code word following closely is second composite signal; It is characterized in that decoding step is as follows:

1) from first composite signal, deducts specific control code word, thereby decode the first signal X ₁Perhaps secondary signal X ₂

2) according to decoded information, another signal of decoding from second composite signal;

Describedly from first composite signal, deduct specific control code word, thereby decode the first signal X ₁Perhaps secondary signal X ₂, comprising:

1) from first composite signal, deducts specific control code word;

2) first composite signal is deducted the signal of controlling the code word gained and obtain the first signal X through function f (x) map decoding ₁Perhaps secondary signal X ₂Value, obtain a control information of another not decoded signal simultaneously, wherein the independent variable of f (x) is the signal that first composite signal deducts control code word gained;

Described according to decoded information, another signal of decoding from second composite signal comprises:

1) decoded signal is shone upon through function u (x);

2) will be through the signal and the second composite signal addition of function u (x) mapping gained;

3) utilize the signal of addition gained and an above-described control information another signal of decoding.

2. a comentropy keeps the device of decoding, comprises that the code word of input looks into the table look-up device of two-dimensional variable length decoding table, if code word of extracting from code stream and the signal combination { X in the code table ₁=x _n, X ₂=y _mCorresponding one by one, then decode signal combination { X ₁=x _n, X ₂=y _m; If the code word of input not with the two-dimensional variable length decoding table in signal combination { X ₁, X ₂Corresponding one by one then with this enter code word and next code word input Deplexing apparatus following closely, it is characterized in that:

1) is used to separate the Deplexing apparatus of first composite signal and second composite signal;

2) deduct specific control code word from first composite signal, the first signal X is used to decode ₁Perhaps secondary signal X ₂Information extracting device;

3) according to decoded information, the information reverting device of another signal of decoding from second composite signal;

Deplexing apparatus links to each other with the information reverting device with information extracting device respectively, and the control code word connects the input of information extracting device, and information extracting device links to each other with the information reverting device.

3. a kind of comentropy according to claim 2 keeps the device of decoding, it is characterized in that described information extracting device, comprising:

1) substracting unit (701);

2) be used to realize function f (x) function, decoding X ₁Or X ₂, obtain the first information reduction apparatus (703) of a control information of another not decoded signal simultaneously;

When the output of table look-up device was the control code word, first composite signal and control code word connect the input of substracting unit (701) respectively; The output of substracting unit (701) links to each other with first information reduction apparatus (703); The X of first information reduction apparatus (703) output ₁Or X ₂, and control information links to each other with the information reverting device.

4. a kind of comentropy according to claim 2 keeps the device of decoding s, it is characterized in that described information reverting device, comprising:

1) adder (704);

2) be used to realize the mapping device (705) of function u (x) function;

3) be used to the X that decodes ₂The second information reverting device (706);

The X of information extracting device decoding gained ₁Or X ₂Connect the input of mapping device (705); The output of mapping device (705) and adder (704) input link to each other; Second composite signal connects another input of adder (704); Adder (704) links to each other with the second information reverting device (706); The control signal of information extracting device output links to each other with the second information reverting device (706), is used for control information transmission; The second information reverting device (706) output X ₂

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